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1

GTZ SUN ENERGY Project

Water Boiling Test Results

Institutional Rocket and Tikikil Stoves

(Draft)

February 2010

ERG Ethio Resource Group

ኢ ት ዮ ሪ ሶ ር ስ ግ ሩ ፕ

2

Deluxe Tikikil-1

Deluxe Tikikil-2

Double skirt Tikikil

1. Introduction

This report presents Water Boiling Test (WBT) results of five different types of household and

institutional rocket stoves. Each of these stoves are described below.

Deluxe Tikikil

An assessment has been conducted in early November 2009 to evaluate Tikikil and institutional rocket

stove producers and users. Some of the feed-backs obtained from Tikikil stove users indicated the need

for a bigger version of Tikikil to accommodate larger pots. During the assessment, it was also learnt that

Tikikil, which was initially designed for household use, is also used by commercial users such as hotels

and restaurants. When it comes to the application of household Tikikil for hotels and restaurants, it has

two major limitations. First, the existing sheet metal the crown part of the stove is made up with is

primarily designed for household use. Thus, it will not last longer with the intensity and frequency of use

in commercial establishments. Secondly, pots with capacity of 10 liters and above, with diameter of about

30 centimeters and larger, are commonly used in restaurants and hotels. The household Tikikil

accommodates pot sizes of 25 centimeter in diameter and smaller. To address this market segment, a more

robust Tikikil is designed and manufactured with a sheet metal of 1 mm thickness. It accommodates pot

sizes of 32 cm in diameter and smaller. Because of its convenience for commercial application in terms of

accommodating larger pot sizes and robustness, it was given the name Deluxe. Two variation of Delux

Tikikil were manufactured.

Deluxe Tikikil 1-

It uses the standard clay liner used for the

household rocket stove. Production of the

stove is using cut templates for different

parts of the stove. The base plate does not

have the cement mix insulation.

Deluxe Tikikil 2 -

Production method of this stove is similar

to that of institutional rocket stove. The

height of the clay liner and the fuel inlet

are slightly increased by 60 mm and 40

mm respectively compared to that of

standard liner for household Tikikil. This

is to avoid the need for frequent removal

of ash during longer cooking.


Double skirt Tikikil is primarily designed to meet the request from

households in refugee settlements in Ethiopia. Unlike most households in

Ethiopia, these refugee households use larger pot sizes for their daily

cooking. This stove has two skirts - a fixed larger skirt and a smaller

removable one. With a larger skirt, it accommodates pots as big as 27 cm

diameter. The smaller skirt is used when smaller size pots are used. The

materials used for the production of double skirt Tikikil are similar to that

used for ordinary household Tikikil.

3

CIRS

IRS

Chimney Institutional Rocket Stove (CIRS)

Along with the chimneyless institutional rocket

stove (IRS), an institutional rocket stove with

chimney has been manufactured. The CIRS

manufactured has an 18 cm by 18 cm combustion

chamber with a power to cook up to 120 liters of

food. IRS greatly reduces smoke or indoor air

pollution (IAP) level in a kitchen but CIRS totally

eliminates it.

CIRS has inner and outer skirts with insulative

material in between to protect the outer skirt from

heating up.

Deluxe Tikikil -1 Deluxe Tikikil - 2 Double skirt Tikikil Institutional Rocket stove

with chimney

2. Test Methodology

Shell Foundation Household Energy Project (SF HEP) WBT version 3 test protocol was used to evaluate

the performances of the stoves. A pot size of 32 cm diameter and ten litres of water was used to test

Deluxe Tikikil stoves. These results were also compared against that of a carefully tended Open Fire

tested with 10 liters of water. The double skirt stove was tested with the smaller skirt using a 24 cm

diameter pot with five litres of water. These results were also compared with earlier results of ordinary

single skirt household Tikikil. Three tests were conducted on each of these stoves.

The chimney institutional rocket stove was also tested using the same SF HEP protocol. Even though SF

HEP is primarily designed for testing household stoves, the principles can also be applied for testing

institutional stoves. However, in the absence of larger capacity weighing balance, SF HEP protocol is not

convenient to apply for testing institutional stoves with very large volume of water. Measuring such a

large volume of boiling water in a similar way as in the case of the household stove is difficult and

unsafe. Alternatively, the total weight of the water can be obtained by weighing and adding several

4

smaller volumes with a bucket. This method, however, is time taking and allows so much of the water to

evaporate unaccounted affecting the accuracy of the results to a greater significance.

In the method applied for testing CIRS, the pot was filled with measured amount of 90 kg of water at the

beginning. The pot was neither weighed nor removed from the stove. Instead the depth of the water was

measured and the weight was calculated. This tells exactly the volume and the weight of water at the

original height Based on the temperature of the water and the drop in height the volume and hence the

weight of evaporated water can pretty easily calculated. This method provides a better accuracy. Three

tests were also conducted. Test results of IRS and Open Fire tested with 75 liters of water are also

presented in this report.

Additional three tests were conducted with CIRS using a different WBT procedure. The purpose of

conducting these test were to compare the performance of institutional rocket stoves with the results of

another type of locally manufactured institutional stove and Open Fire tested several years before1. The

procedure used to test the locally made institutional stove and Open Fire was tailored to resemble the

actual cooking practice of the end users that the stoves were proposed to. With this WBT procedure a

known mass of water was boiled and simmered for 45 minutes. Measurements were taken only at the

beginning and end of the test after completion of the simmering phase without any interruption in

between. The time taken to boil the water is the only intermediate data taken. The amount of fuel

consumed was adjusted for moisture contents and remaining char embers. From this test, the overall

efficiency of the stove and the fuel consumption index were calculated. See explanation of results in the

Annex 1.

3. Performances of stoves

A. Time to boil

The time taken to bring a liter of water to boiling temperature is depicted for each stove in the graph

below.

1 The Test Programme for Turbo Stove within the UN World Food Programme’s Refugees Project and School

Feeding Project in Ethiopia, Result on the Water Boiling Test, UNWFP, Addis Ababa, Ethiopia,29/March/2001.

0.62 0.73

4.11

4.56

2.54

4.77

4.27

0.56 0.58

2.813.05

2.56

3.363.07

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

CIR

S -

90

lite

rs

IRS

-7

5

lite

rs

De

luxe

1 -

10

lit

ers

De

luxe

2 -

10

lit

ers

Op

en

Fir

e

-1

0 l

ite

rs

Do

ub

le

skir

t T

ikik

il

-5

lit

ers

Tik

ikil

-5

lite

rs

Tim

e t

o b

oil

pe

r li

ter

(min

ute

s)

Cold start

Hot start

For the institutional stoves and Open Fire, the boiling time is similar in both cold and hot start phases. In

the case of the institutional stoves, the heat taken up by the liner and insulation mass is

compared to the amount of heat released.

power phase becomes unnoticed when distributed to the

does not have any mass to heat up, the cold and hot start phases are

however, a small difference due to the heating up of the pot supports and the ground.

Double skirt Tikikil stoves, however,

they did in the hot start phase. This is mainly due to the amount of heat that was partly taken to heat up

the clay liner mass during the cold start high powe

The boiling time per liter of water is less than a minute for both institutional stoves. There is no

significant difference between CIRS and IRS in terms of boiling time

Comparison of the two Deluxe Tikikil stoves shows that Deluxe Tikikil

boil a liter of water in cold start when compared to Deluxe Tikikil

significant difference between the two stoves.

less time to boil a liter of water compared to th

phase. Comparison of time to boil a liter of water by Open Fire to that of Deluxe Tikikil stove

start phase shows that Open Fire took from 1.5 to 2 minutes less time.

The boiling time taken by Double skirt Tikikil

significant compared to ordinary household Tikikil

B. Fuel consumption

Fuel consumption refers to the amount of fuel consumed to bring a liter of water to boiling temperature.

The figure below shows the fuel consumed by each stove to boil a liter of water.

48 49

48 49

14 30

0.0

50.0

100.0

150.0

200.0

250.0

300.0

350.0

400.0

CIR

S -

90

lite

rs

IRS

-7

5

lite

rs

Fu

el to

bo

il o

r s

imm

er

1 L

ite

r (g

)

Fuel to simmer

Fuel to Boil Hot Start

Fuel to Boil Cold Start


institutional stoves, the heat taken up by the liner and insulation mass is

compared to the amount of heat released. Moreover, the slight decrease in time to boil during the hot

power phase becomes unnoticed when distributed to the total volume of water boiled. Si

does not have any mass to heat up, the cold and hot start phases are almost similar.

however, a small difference due to the heating up of the pot supports and the ground. Delux

, however, took more time to boil a liter of water in the cold start phase than


during the cold start high power phase.


significant difference between CIRS and IRS in terms of boiling time per liter of water.

Comparison of the two Deluxe Tikikil stoves shows that Deluxe Tikikil-1 takes half a minute less time to

boil a liter of water in cold start when compared to Deluxe Tikikil-2. During hot start, there is no

significant difference between the two stoves. Open Fire with 10 liters of water took about half a minute

less time to boil a liter of water compared to that of Deluxe Tikikil stoves in the high power hot start

Comparison of time to boil a liter of water by Open Fire to that of Deluxe Tikikil stove

start phase shows that Open Fire took from 1.5 to 2 minutes less time.

The boiling time taken by Double skirt Tikikil is slightly longer, less than half a minute, but not

significant compared to ordinary household Tikikil.


The figure below shows the fuel consumed by each stove to boil a liter of water.

71 77

132

81

64 70

146

72

55 49

85

106

De

luxe

1 -

10

lit

ers

De

luxe

2 -

10

lit

ers

Op

en

Fir

e -

10

lit

ers

Do

ub

le

skir

t T

ikik

il

-5

lit

ers

Fuel to Boil Hot Start

Fuel to Boil Cold Start

5


institutional stoves, the heat taken up by the liner and insulation mass is almost negligible

he slight decrease in time to boil during the hot

of water boiled. Since Open Fire

similar. There could be,

Deluxe Tikikil and

took more time to boil a liter of water in the cold start phase than



1 takes half a minute less time to

2. During hot start, there is no

n Fire with 10 liters of water took about half a minute

in the high power hot start

Comparison of time to boil a liter of water by Open Fire to that of Deluxe Tikikil stoves in the cold

is slightly longer, less than half a minute, but not


75

77

64

-5

lit

ers

Tik

ikil

-5

lite

rs

6

Institutional Rocket Stoves

In terms of fuel consumption, the two institutional stoves performed similar in both high power cold start

and hot start phases. For the simmering phase, CIRS took 14 grams of fuel per liter of water simmered.

This is less by half than that consumed by IRS. Both CIRS and IRS have similar size of combustion

chambers which are designed to cook from 90 to 120 liters of food. With 75 liters of water, IRS definitely

performed under capacity, and this could have led to the evaporation of more water. Moreover, IRS was

simmering at higher fire power than CIRS was doing. These are the main reasons for the higher

consumption of fuel in the simmering phase of IRS compared to that of CIRS. The table below shows the

percentage difference between the stoves by fuel consumption and thermal efficiencies.

Type of Test

Fuel consumption (gm/ liter) Efficiency (%)

CIRS - 90 liters IRS - 75 liters CIRS - 90 liters IRS - 75 liters

High Power cold start 47.80 49.19 0.41 0.42

High power hot start 48.19 48.50 0.40 0.48

Simmering 13.78 29.53 0.44 0.39

% Diff. high power cold start 2.8 2.0

% Diff. high power hot start 0.7 17.4

% Diff. simmering 53.3 10.3

Comparison of stoves with different amount of water might not be accurate but could be indicative of the

performances of the stoves.

Deluxe Tikikil Stoves

Comparison of the two Deluxe Tikikil stoves by fuel consumption indicates a slight but not significant

difference in all the three phases. During the high power phases, Deluxe Tikikil 1 took less fuel but the

consumption seemed to have increased in the simmering phase. The high power fuel consumption by

Open Fire, tested with 10 liters of water, is almost double to that of the Deluxe Tikikil stove. See table

below for the comparison of Deluxe stoves and Open Fire.

Type of Test Fuel consumption (gm/ liter) Efficiency (%)

Deluxe 1

- 10 liters

Deluxe 2 -

10 liters

Open Fire

- 10 liters

Deluxe 1 -

10 liters

Deluxe 2 -

10 liters

Open Fire

- 10 liters2

High Power cold start 70.73 76.72 132.12 0.34 0.31 0.17

High power hot start 63.92 69.60 146.18 0.34 0.32 0.15

Simmering 55.14 49.06 85.26 0.34 0.35 0.24

% Saving - cold start 46.5 41.9 51.8 46.3

% Saving - hot start 56.3 52.4 56.5 53.8

% Saving - simmering 35.3 42.5 30.3 32.2

As indicated in the above Table, the fuel saving by the Deluxe Tikikil stoves over Open Fire is higher in

the high power phases ranging from 42 to 56%. The saving is reduced to 35% and 43% for Deluxe 1 and

Deluxe 2 respectively. Fuel saving calculated from the thermal efficiency is also presented in the table

above for comparison. The comparison by thermal efficiency accounts the fuel consumed and the amount

of water evaporated as well.

2 Note that the higher efficiencies in Open Fire are the result of extremely careful tending of the fire. Efficiencies as

low as 10 to 12% were also obtained in previous tests with more relaxed fire tending.


Double skirt Tikikil consumed 10 gram less fuel per liter of water boiled in the hot start phase compared

to that it consumed in the cold start phase. In the simmering phase, unlike the institutional and Deluxe

Tikikil stoves, double skirt Tikikil consumed more fuel to simmering than

partly due to the difficulty to reduce and maintain the firepower to the minimum required. In other words,

the minimum power maintained during the simmering phase

than it was with 10 liters. Hence, more water is evaporated with smaller volume of water which makes the

fuel consumption per liter of water simmered higher.

household Tikikil showed fuel consumption per liter of water simmered as low as 64 grams. See the

graph above.

Comparison of double skirt Tikikil and

presented in the Table below. Percentage fuel saving is calculated based on fuel consumpt

thermal efficiencies.

Type of Test

Double skirt

Tikikil

High Power cold start

High power hot start

Simmering

Diff. high power cold start

Diff. high power hot start

Diff. simmering

The fuel consumption indexes of both cold and hot start high power tests show small differences between

the double skirt Tikikil and the single skirt Tikikil stoves. However, the difference in the simmering phase

is significant. On the other hand, comparis

stoves are similar in the simmering phase as well.

differences in tending the fire.

C. Fire power

Fire power indicates the rate at which the fuel

the stoves discussed in this report.

23662

20615

2662325448

8248

16633

0

5000

10000

15000

20000

25000

30000

CIRS -

90 liters

IRS -75

liters

Fir

ep

ow

er

(Wa

tts)

10 gram less fuel per liter of water boiled in the hot start phase compared

consumed in the cold start phase. In the simmering phase, unlike the institutional and Deluxe

irt Tikikil consumed more fuel to simmering than to boil a liter of water. This is

to reduce and maintain the firepower to the minimum required. In other words,

during the simmering phase was slightly higher when

10 liters. Hence, more water is evaporated with smaller volume of water which makes the

fuel consumption per liter of water simmered higher. However, previous test results with single skirt

il showed fuel consumption per liter of water simmered as low as 64 grams. See the

Comparison of double skirt Tikikil and single skirt household Tikikil, both tested with 5 liters of water, is

Percentage fuel saving is calculated based on fuel consumpt

by fuel consumption by efficiency

Double skirt

Tikikil - 5 liters

Tikikil –

5 liters

Double skirt

Tikikil - 5 liters

80.93 75.18 0.28

72.32 76.88 0.29

106.16 63.92 0.28

-7.7 5.8

5.9 12.3

-66.1 -8.0



On the other hand, comparison by the efficiency terms shows that perform

stoves are similar in the simmering phase as well. This difference, therefore, could be

ire power indicates the rate at which the fuel burns. The Table below shows the fire power for each of

5134 5042

15942

51816961 7091

17413

6850

16633

3251 29224981

2870

Deluxe 1

-10 liters

Deluxe 2

-10 liters

Open Fire

-10 liters

Double

skirt

Tikikil -

5 liters

High Power-Cold start

High Power-Hot Start

Simmering

7

10 gram less fuel per liter of water boiled in the hot start phase compared

consumed in the cold start phase. In the simmering phase, unlike the institutional and Deluxe

boil a liter of water. This is

to reduce and maintain the firepower to the minimum required. In other words,

when simmering 5 liters

10 liters. Hence, more water is evaporated with smaller volume of water which makes the

However, previous test results with single skirt

il showed fuel consumption per liter of water simmered as low as 64 grams. See the

, both tested with 5 liters of water, is

Percentage fuel saving is calculated based on fuel consumption index and

by efficiency

Tikikil –

5 liters

0.26

0.25

0.30

5.8

12.3

8.0



that performances of these

, therefore, could be primarily due to

The Table below shows the fire power for each of

54107528

28701888

5 liters

Tikikil -

5 liters

In general, the fire power during the hot start high power phase was always higher than that of the cold

start in all stoves. The hot liners in rocket stoves

Fire, seem to have contributed for an enhanced rate of fuel burning. This was the primary reason for

shorter boiling time in the hot start phase.

Institutional rocket stoves

Fire powers for the institutional stoves

for IRS and CIRS respectively. The corresponding fire powers for the hot start phase are 25

26.7kW accordingly. During simmering phase the fire power for CIRS is 8

16.6kW. CIRS seems to have been more carefully tended than IRS as the fire power for IRS is much

higher.

Deluxe Tikikil stove

In all three phases the two Deluxe Tikikil stoves have sim

high power cold star, hot start, and simmering phases are 5kW, 7kW and 3kW respectively.

Open fire, with same 10 liters of water, showed 16kW, 17kW and 5kW fire power for the high power cold

start, hot start and simmering phases respectively.

Double Skirt Tikikil

The fire power for double skirt Tikikil is

start and simmering phases. The fire power for

5.4kW, 7.5kW and 1.9kW for the cold start, hot start and simmering phases respectively.

that Tikikil has been more carefully tended resulting in a firepower lower by 1kW than that of the double

skirt Tikikil

D. Turndown ratio

Turndown ratio is the ratio of firepower at high power to that of simmering.

of the stove for regulating the fire power.

with capacities of burning fuel at very

depends on how well the fire is tended.

turndown ratio. The figure below shows the trundown r

3.0

1.2

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

CIRS -90

liters

IRS -75

liters

Tu

rn-d

ow

n-r

ati

oIn general, the fire power during the hot start high power phase was always higher than that of the cold

all stoves. The hot liners in rocket stoves, and perhaps the hotter ground and pot supports in Open

seem to have contributed for an enhanced rate of fuel burning. This was the primary reason for

shorter boiling time in the hot start phase.

institutional stoves during high power cold start phase are about 20.6

respectively. The corresponding fire powers for the hot start phase are 25

simmering phase the fire power for CIRS is 8.2kW while that of IRS is

kW. CIRS seems to have been more carefully tended than IRS as the fire power for IRS is much

In all three phases the two Deluxe Tikikil stoves have similar fire power. The fire power obtained for the

hot start, and simmering phases are 5kW, 7kW and 3kW respectively.


and simmering phases respectively.

The fire power for double skirt Tikikil is 5.2kW, 6.9kW and 2.9kW corresponding to the cold start, hot

start and simmering phases. The fire power for single skirt Tikikil, with the same 5 liters of water,

kW for the cold start, hot start and simmering phases respectively.


Turndown ratio is the ratio of firepower at high power to that of simmering. It is a measure of flexibility

of the stove for regulating the fire power. In principle, higher turndown ratio can be ob

of burning fuel at very high and very low rates. In practice, with solid fuels

depends on how well the fire is tended. With extremely careful fire tending, an Open Fire can have higher

turndown ratio. The figure below shows the trundown ratio for the stoves tested.

1.61.8

3.2

1.9

Deluxe 1 -10

liters

Deluxe 2 -10

liters

Open Fire -

10 liters

Double skirt

Tikikil -5

liters

8

In general, the fire power during the hot start high power phase was always higher than that of the cold

, and perhaps the hotter ground and pot supports in Open

seem to have contributed for an enhanced rate of fuel burning. This was the primary reason for

0.6kW and 23.7kW

respectively. The corresponding fire powers for the hot start phase are 25.4kW and

kW while that of IRS is

kW. CIRS seems to have been more carefully tended than IRS as the fire power for IRS is much

ilar fire power. The fire power obtained for the

hot start, and simmering phases are 5kW, 7kW and 3kW respectively.


kW corresponding to the cold start, hot

, with the same 5 liters of water, was

kW for the cold start, hot start and simmering phases respectively. It can be noted


It is a measure of flexibility

igher turndown ratio can be obtained with stoves

with solid fuels it is very much

With extremely careful fire tending, an Open Fire can have higher

4.1

liters

Tikikil -5

liters

9

CIRS and Open Fire with 10 liters of water showed bigger turndown ratio. However, the level of effort in

regulating the fire in Open Fire was extremely tedious. An Open Fire, without additional tending effort,

can have a turndown ratio as low as 1.3. Both Deluxe Tikikil stoves have similar turndown ratio.

4. Conclusion and Recommendation

The findings of this and previous WBT tests show that Tikikil and the institutional rocket stoves showed

fuel savings of 40% and above over extremely carefully tended Open Fire. More fuel saving could be

achieved in actual cooking conditions in the households where fuel tending with Open Fire is often less

careful. It is time now to verify the WBT results of Tikikil with actual cooking by conducting controlled

cooking tests (CCT) to be followed by a kitchen performance test (KPT).

With regard to the Deluxe Tikikil stoves, the project team needs to decide on one for further CCT, KPT or

promotion. In terms of performance both prototypes of Deluxe Tikikil stoves are similar. Considering,

ease of production and costs, the one labled Deluxe Tikikil-1 seems to have taken less material. In

addition to this, Deluxe Tkikikil-1 is easier to manufacture as it uses the standard household liner and that

parts are assembled from pre-cut templates. It can be manufactured by both Tikikil and IRS producers.

On the other hand, larger fuel inlet on Deluxe Tikikil-2 makes ash and embers removal from the

combustion chamber easier. However, the need for a longer liner and the relatively more time taking

manufacturing process are drawbacks. It can only be manufactured by IRS producers. Based on these

criteria Deluxe Tikikil-1 seems more appropriate for further promotion.

For the chimney institutional stove, the appropriate chimney height may need to be identified. Unlike the

case in households, kitchen heights in institutions vary greatly. The prototype chimney institutional rocket

stove was tested with a chimney riser height of about two meters. A two meter chimney height would still

keep the smoke under the roof in most institutional kitchens. For complete elimination of smoke from a

kitchen, a chimney height of at least three meters is needed. The effect of the additional chimney could

affect the performance of the stove. Therefore, it is worth that the project team should assess and identify

the typical chimney height appropriate for most institutional kitchens and conduct WBT to determine its

performance.

10

Annex A1: Comparison of CIRS and other stoves using a different procedure

Additional three tests were conducted with CIRS using a different WBT procedure. The purpose of

conducting these tests were to compare the performance of institutional rocket stoves with the results of

another type of locally manufactured institutional stove and Open Fire tested several years before using a

different procedure3. The locally manufacture improved institutional stove was also a sunken-pot type but

different from rocket stoves. This procedure was tailored to resemble the actual cooking practice of the

end users in Bonga refugee settlements who were using the Open Fire stove for mass cooking. With this

WBT procedure, a known mass of water was boiled and simmered for 45 minutes. Measurements were

taken only at the beginning and end of the test after completion of the simmering phase without any

interruption in between. The time taken to boil the water was the only intermediate data taken. The

amount of fuel consumed was adjusted for moisture contents and remaining char embers. From this test,

the overall efficiency of the stove and the fuel consumption index were calculated.

Since the test results were taken from different sources, the weight of water that the stoves were tested is

not similar. The locally made institutions stove and Open Fire were tested with 80 liters of water. The

chimneyless institutional stove (IRS) results were deducted by combining the high power cold start phase

and the simmering phase from previous test results with 75 liters of water. Since all stoves are not tested

with equal amount of water, the presentation below should rather be taken as an indication of their

performances rather than a comparison.

The performances of the stoves are described in terms of fuel consumption, overall thermal efficiency,

time required to bring a litre of water to boil and fire power. The results are discussed below. Note that

Fuel Consumption

The fuel consumption by each stove to boil and simmer a litre of water is presented in Figure A1.1 below.

Fuel consumption in this case is calculated by dividing the equivalent dry wood consumed by the amount

of water remaining at the end of the simmering phase. Since a certain mass of water is evaporated during

the test, the final weight of water is always less than the initial weight of water. The calculation for the

fuel consumption index doubly discredits the stoves performance as it does not account the energy

consumed to evaporate the water.

Figure A1.1: Fuel consumption to boil and simmer one litre of water

3 The Test Programme for Turbo Stove within the UN World Food Programme’s Refugees Project and School

Feeding Project in Ethiopia, Result on the Water Boiling Test, UNWFP, Addis Ababa, Ethiopia, March 2001.

128

93 8259

0

20

40

60

80

100

120

140

Open

Fire

Local Improved

Inst. Stove

Rocket

Stove no

chimney

Rocket stove with

chimneyFu

el

to b

oil

an

d s

imm

er

(gm

/l)

11

CIRS seems to have consumed the least amount of fuel per litre of water boiled and simmered (59gm/l)

compared to the other stoves. The rocket stove without chimney (IRS) consumed more fuel, 82gm/l, than

CIRS to simmer a liter of water. One of the reasons for the low performance of IRS could be that the

stove was a little bit oversized to boil 75 liters as it is primarily designed for 90 to 120 litres of water.

Compared to CIRS, IRS evaporated 2kg of more water. Open Fire and the locally manufactured

institutional stove consumed 128gm/l and 93gm/l respectively.

Overall Thermal Efficiency

The performances of the stoves in terms of overall thermal efficiencies are presented in Figure A1.2

below.

Figure A1.2: Overall thermal efficiency of the stoves

As can be seen from the Figure above, Open Fire performed the lease with an overall efficiency of 24%.

The highest efficiency is obtained by CIRS followed by IRS and the local institutional stove with thermal

efficiencies of 44.1%, 40.4% and 32% respectively.

Fuel Saving Compared to Open Fire

Fuel savings of the improved stoves were compared against that of Open Fire. As mentioned above, this

comparison may not be very accurate as each stove was tested with different weight of water but is

indicative to estimate the relative fuel savings. Table A2.1 below shows the relative fuel saving in terms

of fuel consumption index and thermal efficiencies. Thermal efficiency accounts the energy consumed per

output more accurately than fuel consumption index. However, in reality, most cooking might not need to

evaporate more water and hence accounting the amount of water evaporated might not be needed. In this

case, the fuel consumption index should be taken as the governing indicator of stove performance. It is

also important to compare stoves in terms of thermal efficiency as it accounts energy input and output

more precisely.

24.0

32.4

40.4

44.1

20.0

25.0

30.0

35.0

40.0

45.0

Open

Fire

Local Improved

Inst. Stove

Rocket

Stove no

chimney

Rocket stove with

chimney

Th

erm

al

Eff

icie

ncy

(%

)

12

Table A2.1: Comparison of stoves with Open Fire

Fuel saving over Open Fire

Stove Type

Local Improved

Inst. Stove

Rocket Stove

With no chimney

Rocket stove

with chimney

Based on specific fuel consumption 27.6% 36.2% 54.0%

Based on thermal efficiency 25.9% 40.5% 45.4%

The fuel saving over open fire, based on specific fuel consumption to boil and simmer a litter of water is

54%, 36.2% and 27.6% for CIRS, IRS and Locally manufactured improved institutional stove respectively.

On the other hand, the fuel saving over open fire based on thermal efficiencies is 45.4%, 40.5% and

25.9% for CIRS, IRS and the local made improved institutional stove accordingly.

Time to Boil

Figure A1.3 below shows the time taken by each stove to bring one litre of water to boiling. In should be

noted that all stoves took less than one minute to bring a litre of water to boiling temperature. Open Fire

taking 0.93 minutes was the longest time taken to boil.

Figure A1.3: Time required to boil one litre of water

Local institutional stove took the shortest time to boil a liter of water, 0.60 minute, followed by CIRS and

IRS each taking 0.62 minute and 0.74 minute respectively.

Fire Power

The firepower for each stove is indicated in Figure A1.4. Open Fire showed the highest fire power

24.6kW followed by the locally designed improved stove, 23kW. The rocket stoves with and without

chimney showed similar firepower of 16 and 17kW respectively.

0.93

0.60

0.74

0.62

0.40

0.50

0.60

0.70

0.80

0.90

1.00

Open

Fire

Local Improved

Inst. Stove

Rocket

Stove no

chimney

Rocket stove with

chimney

Tim

e t

o b

oil

(m

in/l

ite

r)

13

Figure A1.4: Fire Power for different stoves

However, the firepower by IRS for 75 liters of water is much higher than that of CIRS for 90 liters of

water. This could also be another reason for evaporation of more water in IRS.

24.6 22.9

17.2 15.6

0.0

5.0

10.0

15.0

20.0

25.0

Open

Fire

Local Improved

Inst. Stove

Rocket

Stove no

chimney

Rocket stove with

chimney

Fir

e P

ow

er

(kW

)

14

Annex A2: Raw data

Type of Test

units

CIRS

IRS

1. HIGH POWER TEST (COLD

START)

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev

Temperature corrected time to boil

min

57.01

54.08

56.76

55.95

1.62

54.99

54.76

53.73

54.49

0.67

Burning rate

g/min

71.94

78.47

75.66

75.36

3.28

71.58

70.29

55.09

65.65

9.17

Thermal efficiency

--

0.41

0.40

0.41

0.41

0.00

0.42

0.40

0.42

0.42

0.01

Specific fuel consumption

g/litre

47.06

50.20

49.38

48.88

1.63

52.32

53.78

40.14

48.75

7.49

Temp-corrected specific consumption g/litre

46.38

48.15

48.86

47.80

1.28

54.81

53.14

39.61

49.19

8.33

Firepower

watts

22,587.59

24,639.82

23,757.56

23,661.66

1,029.47

22476.42

22072.25

17297.13

20,615.27

2,880.69

2. HIGH POWER TEST (HOT

START)

units

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev


min

51

52

48

50.32

1.98

40.51

50.39

38.96

43.29

6.20

Burning rate

g/min

79

82

93

84.79

6.92

84.55

69.06

89.53

81.04

10.67

Thermal efficiency

--

0.42

0.39

0.39

0.40

0.02

0.51

0.49

0.46

0.48

0.02


g/litre

43

46

49

46.07

3.02

45.37

46.01

47.08

46.15

0.87


46

48

51

48.19

2.36

48.47

48.67

48.37

48.50

0.15

Firepower

watts

24,917

25,885

29,067

26,623.11

2,171.44

26547.26

21684.86

28111.51

25,447.87

3,351.41

3. LOW POWER (SIMMER)

units

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev

Burning rate

g/min

31.73

20.91

26.17

26.27

5.41

60.64

47.86

50.42

52.97

6.76

Thermal efficiency

--

0.50

0.41

0.40

0.44

0.06

0.43

0.34

0.40

0.39

0.04


g/litre

17

11

14

13.78

3.06

22.39

32.08

34.12

29.53

6.27

Firepower

watts

9,962

6,565

8,218

8,248.16

1,699.03

19040.95

15026.53

15831.11

16,632.86

2,123.91

Turn down ratio

--

2.27

3.75

2.89

2.97

0.75

1.18

1.47

1.09

1.25

0.20

15

Type of Test

units

Deluxe Tikikil 1 – 10 liters

Deluxe Tikikil 2 – 10 liters


START)

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev


min

43.55

40.68

38.96

41.06

2.32

43.50

45.82

47.55

45.63

2.03

Burning rate

g/min

16.41

15.88

16.76

16.35

0.44

17.85

15.56

14.77

16.06

1.60

Thermal efficiency

--

0.34

0.35

0.34

0.34

0.00

0.29

0.31

0.32

0.31

0.01


g/litre

73.20

64.67

66.46

68.11

4.50

84.21

72.93

72.15

76.43

6.75


76.25

67.65

68.29

70.73

4.79

81.91

74.72

73.52

76.72

4.54

Firepower

watts

5151.92

4987.00

5261.95

5,133.62

138.38

5,604.81

4,884.64

4,636.30

5,041.92

503.05


START)

units

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev


min

31.53

26.40

26.29

28.07

2.99

34.07

25.04

32.26

30.46

4.78

Burning rate

g/min

19.22

24.43

22.85

22.17

2.67

19.64

29.33

18.77

22.58

5.86

Thermal efficiency

--

0.36

0.32

0.34

0.34

0.02

0.32

0.29

0.34

0.32

0.03


g/litre

60.41

63.74

61.91

62.02

1.67

69.55

74.19

62.41

68.71

5.94


63.19

66.58

61.99

63.92

2.38

69.64

76.43

62.74

69.60

6.85

Firepower

watts

6036.02

7672.31

7175.71

6,961.35

838.94

6,167.22

9,210.83

5,893.97

7,090.67

1,841.18


units

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev

Burning rate

g/min

10.76

11.04

9.26

10.35

0.96

8.38

8.36

11.19

9.31

1.63

Thermal efficiency

--

0.34

0.34

0.34

0.34

0.00

0.35

0.35

0.34

0.35

0.01


g/litre

58.53

59.51

47.38

55.14

6.74

43.99

43.95

59.24

49.06

8.82

Firepower

watts

3379.83

3465.72

2907.60

3,251.05

300.52

2,630.13

2,624.10

3,512.16

2,922.13

510.99

Turn down ratio

--

1.52

1.44

1.81

1.59

0.19

2.13

1.86

1.32

1.77

0.41

16

Type of Test

units

Open Fire – 10 liters


START)

Test 1

Test 2

Test 3

Average

St Dev


min

28.01

24.49

23.78

25.43

2.26

Burning rate

g/min

38.67

55.87

57.77

50.77

10.52

Thermal efficiency

--

0.19

0.15

0.16

0.17

0.02


g/litre

110.58

146.20

140.27

132.35

19.09


111.77

141.67

142.93

132.12

17.64

Firepower

watts

12,142.37

17,543.31

18,139.69

15,941.79

3,303.88


START)

units

Test 1

Test 2

Test 3

Average

St Dev


min

27.71

24.73

24.37

25.61

1.83

Burning rate

g/min

48.42

60.66

57.29

55.46

6.32

Thermal efficiency

--

0.16

0.14

0.15

0.15

0.01


g/litre

135.10

152.00

144.29

143.80

8.46


139.18

154.69

144.67

146.18

7.86

Firepower

watts

15,203.32

19,048.08

17,987.70

17,413.03

1,985.76


units

Test 1

Test 2

Test 3

Average

St Dev

Burning rate

g/min

14.95

14.92

17.72

15.86

1.61

Thermal efficiency

--

0.26

0.23

0.21

0.24

0.02


g/litre

82.20

79.38

94.21

85.26

7.87

Firepower

watts

4,695.05

4,684.11

5,564.58

4,981.25

505.21

Turn down ratio

--

2.59

3.75

3.26

3.20

0.58

17

Type of Test

units

Double skirt Tikikil – 5 liters

Tikikil – 5 liters


START)

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev


min

30.55

21.42

19.65

23.87

5.85

23.00

21.00

20.00

21.33

1.53

Burning rate

g/min

14.42

16.36

18.72

16.50

2.15

17.73

15.19

18.76

17.23

1.83

Thermal efficiency

--

0.28

0.27

0.28

0.28

0.00

0.25

0.27

0.26

0.26

0.01


g/litre

92.85

69.46

71.28

77.86

13.01

83.41

64.99

76.71

75.04

9.33


94.10

72.86

75.83

80.93

11.50

79.19

70.64

75.70

75.18

4.30

Firepower

watts

4,527.02

5,138.01

5,876.72

5,180.58

675.86

5,568.45

4,771.01

5,889.38

5,409.61

575.86


START)

units

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev


min

22.60

14.28

13.46

16.78

5.06

16.00

15.00

15.00

15.33

0.58

Burning rate

g/min

16.26

23.24

25.95

21.81

5.00

22.20

22.50

27.23

23.98

2.82

Thermal efficiency

--

0.29

0.29

0.28

0.29

0.01

0.27

0.26

0.22

0.25

0.03


g/litre

75.57

65.90

67.07

69.51

5.28

72.49

68.59

83.19

74.76

7.56


76.38

69.13

71.45

72.32

3.71

70.61

74.55

85.47

76.88

7.70

Firepower

watts

5,104.07

7,297.31

8,147.82

6,849.73

1,570.46

6,970.80

7,063.74

8,550.85

7,528.46

886.63


units

Test 1

Test 2

Test 3

Average

St Dev

Test 1

Test 2

Test 3

Average

St Dev

Burning rate

g/min

10.90

9.71

6.81

9.14

2.10

6.10

6.95

4.98

6.01

0.99

Thermal efficiency

--

0.27

0.27

0.29

0.28

0.01

0.30

0.28

0.32

0.30

0.02


g/litre

131.48

113.75

73.24

106.16

29.85

64.94

74.34

52.50

63.92

10.96

Firepower

watts

3,422.78

3,048.92

2,137.87

2,869.85

660.91

1,916.66

2,183.77

1,564.14

1,888.19

310.79

Turn down ratio

--

1.32

1.69

2.75

1.92

0.74

3.64

3.23

5.47

4.11

1.19

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